Conventional server units include bays for installation of media drives such as hard disk drives (HDDs) where each drive is typically carried in its own tray. Trays often include guides such as rails that fit into slots of a bay. Sometimes, slots are symmetrical, which allows for installation of a tray assembly in more than one orientation. Multiple orientations can cause confusion when trying to locate and replace a media drive seated in a server unit, especially where the unit is in a server rack or server tower that includes multiple units. As described herein, various keyed components ensure that media drives are seated in a relatively uniform manner in a server unit and optionally further ensure that only certified media drive assemblies are used.